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Reverse Engineering AWS Resources using AWS CloudFormation IaC Generator

Reverse Engineering AWS Resources using AWS CloudFormation IaC Generator

Effortlessly convert AWS infra to code with IaC Generator — a game-changer for automation, version control, and management.

awscommunitycloudformationiac-generatorinfrastructure-as-code
Garre Sandeep
Published Apr 14, 2025

Introduction:

In today’s cloud-native world, Infrastructure as Code (IaC) has become the cornerstone of scalable, repeatable, and secure cloud deployments. It allows teams to define, manage, and provision infrastructure through machine-readable configuration files rather than relying on manual processes.
However, many organizations still operate with manually provisioned AWS resources, especially during early experimentation or legacy setups. This can lead to configuration drift, lack of change visibility, and operational inefficiencies.
To address this challenge, AWS introduced the CloudFormation IaC Generator — a powerful tool that allows users to reverse-engineer existing AWS resources into CloudFormation templates. This not only accelerates the transition to IaC but also promotes consistency, repeatability, and better change management.

🎯 Goal:

To extract an existing ECS/EC2 environment setup into a CloudFormation template, refine it, and redeploy or import it as a stack into another AWS region or environment — enabling a repeatable, consistent deployment model with better change control. ✅
A Practical POC on Infrastructure as Code (IaC) Adoption
🚀 Objective:
In this POC, I focused on reverse-engineering an existing EC2-based infrastructure using AWS CloudFormation’s IaC Generator, refining the generated template, and redeploying the setup — including a Change Control test and multi-region deployment.

AWS Services Involved:

  • Amazon EC2
  • VPC / Subnets
  • Security Groups
  • IAM
  • CloudFormation (IaC Generator)
  • (Optional Enhancements: S3, SNS)

Phase 1: Manual Resource Setup

To simulate a real-world environment:
  • Created a VPC with public subnet & internet gateway
  • Configured a route table and associated it with the subnet
  • Defined a Security Group with inbound SSH/HTTP rules
  • Launched a t2.micro EC2 instance with user data to start an HTTP server

Phase 2: Resource Scan & Template Generation

Using CloudFormation IaC Generator:
  • Navigated to CloudFormation → Create Template from Existing Resources
  • Selected my manually created EC2 instance
  • AWS automatically detected and included:
    • Subnet
    • Internet Gateway
    • Security Group
    • Route Table
  • Generated a downloadable YAML template with the full architecture captured

Phase 3: Template Refinement & Change Control

  • Parameterization: Modified static values (e.g., AMI IDs, instance types)
  • Introduced parameters for cross-region flexibility
  • Tested Change Control by updating the InstanceType from t2.micro to t2.medium using Change Sets
  • Verified seamless update with no manual intervention

Phase 4: Stack Redeployment in Another Region (Ohio)

  • Uploaded the refined CloudFormation template
  • Passed region-specific parameters (e.g., AMI ID, KeyPair)
  • Successfully recreated:
    • EC2 instance
    • VPC + Routing
    • Security Group
  • Validated architecture parity between original and redeployed stacks

Security Considerations:

  • Templates stored in S3 with encryption
  • Bucket policy enforces access via IAM roles only
  • Versioning enabled for audit and rollback
  • Public access disabled on S3 bucket
     

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